Cleaning compositions generally comprise one or more surfactants, and, optionally, one or more hygiene agents.
Typical surfactants are selected from anionic, nonionic, amphoteric and cationic surfactants. Nonionics are very commonly used due to their effectiveness on fatty soils and the ease with which their foaming can be controlled. Of these surfactants, nonionics are reported as showing low biocidal activity, whereas certain anionic, cationic and amphoteric surfactants show biocidal activity under specific conditions of, for example, pH and concentration.
Typical hygiene agents include, strong acids, alkali's, phenolics, and oxidants such as peracids and hypohalites. These are generally highly reactive species which exhibit this reactivity in terms of one or more of, short shelf life, toxic, corrosive and irritant properties. In general, these components are required at relatively high levels in formulations.
Other less chemically reactive hygiene agents, such as 2,4,4'-trichloro-2'-hydroxy diphenyl ether (available in the marketplace as IRGASAN [RTM]), are effective at relatively low concentrations but are more expensive than simpler species and may be specific as regards their spectrum of activity.
In addition to the above, many organic acids, including benzoic, salicylic and sorbic are known as preservatives in cosmetics and some food products. These preservatives generally show lower biocidal activity than the above-mentioned chemically reactive hygiene agents when used at the same level.
A disinfectant can be understood to be a hygiene agent which shows a 100,000 fold or better reduction in the number of viable microorganisms in a specified culture when used at a level of around 0.5 wt %. This is generally known as a `log 5 kill`. Of the organic acids mentioned above, salicylic acid is generally regarded as the most effective biocide against common bacteria, but its activity falls far short of that required of a disinfectant at practical concentrations.
DE 3619375 (Henkel) discloses that alkyl polyglycoside (APG) surfactants show a synergy with alcohols and organic acids as regards hygiene. The examples disclose compositions which comprise APG and organic acids including salicylic acid. These compositions are used at strongly acidic pH, generally below pH 3.
EP 0331489 (PARKE DAVIS PTY.) discloses a formulation for the treatment of acne which comprises a surfactant and a biocide. The examples illustrate the invention by reference to combinations of specific surfactants with specific biocides.
DE 3518929 (Hans-Joachim Gobel) disclose a formulation for the treatment of dandruff which comprises a commercially available hair washing composition, which is identified, but whose composition is not given, and salicylic acid.
RO 64162 (MIRAJ, 1974) discloses an anti-dandruff lotion which contains 10-30% wt ethanol, water, 0.5-3% wt salicyclic acid, 0.5-3% wt fatty acid alkoyl-betaine amide and 0.1-1% wt undecylenic acid monoethanolamide. It is believed that the salicyclic acid in such formulations is present as a keratolytic agent: causing dead skin tissue to be shed.
Hard surface cleaning compositions typically comprise one or more of anionic and nonionic surfactants. Of the nonionics, alkoxylated alcohols, particularly ethoxylated alcohols, are commonly used.